May 17, 2007 -- Blood transfusions containing blood from precancerous donors
do not appear to increase the risk of cancer in the recipients, according to a
new study.

A study of more than 350,000 blood transfusion recipients showed that those
who received blood from precancerous donors had no higher risk of developing
cancer than other transfusion recipients.

Researchers say the findings are reassuring and a major advancement in the
understanding of long-term transfusion-related risks.

"Continuous attention to transfusion safety has reduced the risk of
transfusion-transmitted disease to a current record low," write researcher
Gustaf Edgren, MD, of the Karolinska Institutet in Stockholm, Sweden, and
colleagues. Although most infections and complications have been relatively
easy to identify, the possible transmission of chronic diseases with unknown
causes has been far more difficult to address, they write.

Blood Transfusions and Cancer Risk

The study analyzed data gathered between 1968 and 2002 from computerized
blood bank registers in Denmark and Sweden, including information on 1.13
million blood donors and 1.31 million blood transfusion recipients.

Out of the more than 350,000 recipients included in the final analysis, just
over 12,000 (3%) were exposed to blood products from donors who later went on
to develop cancer.

The blood transfusion recipients were followed for up to 34 years, and the
results showed no increased risk of cancer associated with the exposure.

"Our data provide no evidence that blood transfusions from precancerous
blood donors are associated with an increased risk of cancer among recipients
compared with transfusions from non-cancerous donors," the researchers
conclude.

Thanks to the scope and thoroughness of the study, experts say the results
represent an important step forward in evaluating one of the potential
long-term risks of blood transfusion. But much more is still unknown.

"Blood is an immensely complex and biologically active substance.
Although the potential for standard allogeneic blood transfusion [from unknown
persons] to save lives is incontrovertible, our understanding of the full
consequences of transfusion is rudimentary," writes Garth Utter, MD, of the
University of California, Davis, in a commentary that accompanies the study in
The Lancet.